PROGRAM 2: Oscillatory dynamics: PKA Circadian control as modifiers of mast cell responses. One of the central themes of systems biology is the quantitative analysis of the complex dynamical interactions critical to human health. One important signaling pathway, involving protein kinase A (PKA), mediates the daily changes of light on circadian dynamic control. These oscillations underlie the rhythms in pathologies of cardiovascular disease, cancer, sleep disturbances, depression, and allergic immune responses. In this Program, we will explore the mechanisms of circadian rhythms and dynamic control by PKA and the initiation of allergic immune responses in mammalian mast cells, as well as crosstalk to NF&#954;B mediated inflammation.